Recording parameter setting device and method using pulse sequences

ABSTRACT

A recording parameter setting device setting parameters of pulse sequences forming recording marks on recording media. The device includes a storage section storing first and second look-up tables, and a recording parameter setting section for obtaining from the tables and setting parameters corresponding to recording information. The pulse sequences form at least marks equal to or longer than a first predetermined length but not longer than a maximum mark length, and include top and last sections. Also, the first lookup table stores parameters for top sections that control heat of front edges of marks classified into a same group. The second lookup table stores parameters for last sections for controlling heat of rear edges that are equal to or longer than a second predetermined recording mark length, that is longer than the first predetermined recording mark length, through the maximum recording mark length and classified into a same group.

This application is a divisional application of U.S. application Ser.No. 12/226,353, filed Oct. 16, 2008, and claims the right of priorityunder 35 U.S.C. §119 based on Japanese Patent Application Nos.2006-127063 filed Apr. 28, 2006 and 2007-003859 filed Jan. 11, 2007,which are hereby incorporated by reference herein in their entirety asif fully set forth herein.

TECHNICAL FIELD

The present invention relates to a recording parameter setting devicefor recording and reproducing information, a program thereof, acomputer-readable recording medium containing the program, aninformation recording medium, a recording/reproducing device, and arecording parameter setting method.

BACKGROUND ART

Recording/reproducing devices for an information recording medium (suchas an optical disc) which stores large amount of data haveconventionally adopted an art which records information by focusing alaser beam onto an information recording medium and heating theinformation recording medium, so as to change physical characteristicsof the medium. According to the art, binary digital data is recorded onthe information recording medium. The binary digital data is expressedby (i) two states including a state where a recording mark is formed onthe information recording medium (hereafter, referred to as “mark”) anda state where a recording mark is not formed (hereafter, referred to as“space”) and (ii) each length of the two states. The digital data iscalled “recording information” herein. Actually, the recordinginformation is recorded on the information recording medium such that:(1) a recording parameter is set in accordance with the recordinginformation to be recorded; (2) the recording parameter changes thelaser beam; (3) the laser beam thus changed forms a recording mark onthe information recording medium, thereby recording the recordinginformation on the information recording medium.

In recent years, in response to an increase in the amount of data whichis processed, recording speed is being increased for the purpose ofreducing the processing time of a recording/reproducing device. Evenwhen an information recording medium becomes capable of recording at ahigh speed, the information recording medium needs to be capable ofrecording also at a low speed so as to ensure backward compatibility.Therefore, the information recording medium capable of recording at ahigh speed has a property which is apt to accumulate heat so as toimprove its recording sensitivity. The heat accumulation can distort arecording mark, thereby leading to deterioration in a reproduced signalquality. Therefore, in an information recording medium capable ofrecording at a high speed, it is important to control heat for forming arecording mark.

As an art which is used for controlling heat for forming a recordingmark, there has been known write strategy, which is a high-level laseroutput control technology. The write strategy carries out laser outputcontrol in accordance with the recording parameter so as to control heatfor forming a recording mark. As the number of recording parametersincreases, the control of heat for forming a recording mark becomescomplicated. There is a method where a recording parameter is oncestored in an information recording medium in a form of a look-up table,and the recording parameter is read out from the look-up table by arecording/reproducing device so as to set the recoding parameter. Inthis method, the increased number of recording parameters prolongsread-out time of information from the look-up table by using therecording/reproducing device. This causes delay in the timing ofstarting a recording process. Therefore, it is preferable to use assmall number of recording parameters as possible.

In view of this, for example, Patent Document 1: Japanese UnexaminedPatent Application Publication, No. 2005-92942 (published on Apr. 7,2005) discloses an optical disc recording method including a look-uptable which defines recording parameters. In the method, the procedureof controlling heat for forming a recording mark proceeds while thetable is looked up.

Specifically, Patent Document 1 describes as follows. A recordingparameter for a top pulse which controls heat of a front edge, at whicha forming process of a recording mark starts, uses a look-up table inwhich (i) front space lengths of recording marks are classified intofour groups: 2T, 3T, 4T, and 5T or longer and (ii) recording marklengths are classified into three groups: 2T, 3T, and 4T or longer (seeFIG. 17). Also, a recording parameter for a last pulse which controlsheat of a rear edge, at which a forming process of a recording markends, uses a look-up table in which (i) rear space lengths of recordingmarks are classified into four groups: 2T, 3T, 4T, and 5T or longer and(ii) recording mark lengths are classified into two groups: 3T and 4T orlonger (see FIG. 18). That is, in the look-up table disclosed in PatentDocument 1, mark lengths of 4T or longer are classified into the samegroup, and front and rear space lengths of 5T or longer are classifiedinto the same group. This reduces the number of recording parameters.Thereby, heat for forming a recording mark is controlled at a front edgeand a rear edge. The symbol “T” herein represents a time equivalent toone cycle of a clock. For example, a mark length of 2T indicates aregion (i.e., a recording region) where a recording mark “1” is formedfor a time equivalent to two cycles of the clock. Similarly, a spacelength of 2T indicates a region where no recording mark is formed for atime equivalent to two cycles of the clock.

With a further increase in a recording speed expected in the future, arecording mark will be formed on an information recording medium havingimproved recording sensitivity. When a recording mark is formed by usinga laser beam, heat distribution is high at a rear edge of a recordingmark, at which rear edge the forming process of the recording mark ends.Therefore, the increase in the recording speed will strengthen thetendency to accumulate heat at the rear edge. This leads to anincreasing necessity for controlling heat at the rear edge more strictlyby using the recording parameter.

Patent Document 1, however, uses the same setting for (i) theclassification of recording parameters for controlling heat of a frontedge, at which a forming process of a recording mark starts and (ii) theclassification of recording parameters for controlling heat of a rearedge, which needs to be controlled strictly. Specifically, both types ofthe recording parameters use a look-up table in which recording marklengths of 4T or longer are classified into the same group. In addition,Patent Document 1 does not specifically disclose on what basis therecording mark lengths, the front space lengths, and the rear spacelengths are classified in the look-up table, which defines the recordingparameters, for the purpose of reducing the number of recordingparameters. Therefore, although the number of the recording parametersis reduced, there is a problem that a good reproduced signal quality isnot guaranteed (i.e., a reproduced signal quality as desired is notguaranteed) in reading out a recording mark actually.

DISCLOSURE OF INVENTION

The present invention is made in view of the foregoing conventionalproblem, and has an object for providing: a recording parameter settingdevice configured to form a recording mark capable of surely obtaining agood reproduced signal quality while the number of recording parametersto be used is reduced; a program thereof; a computer-readable recordingmedium containing the program; an information recording medium; arecording/reproducing device; and a recording parameter setting method.

In order to attain the object, a recording parameter setting device ofthe present invention is a recording parameter setting device configuredto set a recording parameter for forming a recording mark on aninformation recording medium in accordance with recording information,comprising: (i) trial recording parameter setting means configured toinquire, in accordance with the recording information, a storage sectioncontaining recording parameters used for controlling heat of recordingmarks, and to set a trial recording parameter for carrying out trialrecording, wherein (a) the recording parameters are used for controllingheat of at least rear edges of the recording marks, at which rear edgesa forming process of the recording marks ends, (b) the recordingparameters are classified in accordance with at least recording marklengths out of the recording information, and (c) recording parametersof a predetermined recording mark length or longer are classified into asame group; and (ii) reproduced signal quality judging means configuredto further classify the recording parameters of the predeterminedrecording mark length or longer into more detailed groups and to causeto carry out the trial recording again if a reproduced signal obtainedby reproduction of the trial recording carried out in accordance withthe trial recording parameter does not satisfy a predeterminedreproduced signal quality, and configured to set the trial recordingparameter as the recording parameter if the reproduced signal satisfiesthe predetermined reproduced signal quality.

With the invention, the recording parameters for controlling the heat ofat least the rear edge of the recording mark are classified into thesame group if the recording mark length is equal to or longer than thepredetermined recording mark length. This reduces the number ofrecording parameters as a whole, compared with a method in which therecording parameters are classified into different groups for everyrecording mark length.

The “classification” is, in other words, grouping in accordance with therecording mark length. Specifically, by the classification, a certainvalue (or a certain amount of change) is given to recording parametersfor recording mark lengths which are put together into one group.

Also, the invention has an arrangement such that (i) the trial recordingparameter setting means sets a trial recording parameter for trialrecording in accordance with recording information; and (ii) thereproduced signal quality judging means judges whether or not thereproduced signal obtained by reproduction of the trial recordingcarried out in accordance with the trial recording parameter satisfies apredetermined reproduced signal quality. The reproduced signal qualityjudging means carries out the followings: if the reproduced signal doesnot satisfy the predetermined reproduced signal quality, the recordingparameters of the predetermined recording mark length or longer arefurther classified into detailed groups in accordance with the recordingmark length, and trial recording is carried out again; and if thereproduced signal satisfies the predetermined reproduced signal quality,the trial recording parameter is set as the recording parameter. Thatis, the process of determining the recording parameter which satisfiesthe predetermined reproduced signal quality proceeds while the number ofclassifications of recording parameters is being increased. This makesit possible to further reduce the number of classifications of recordingparameters in a case where the recording parameter satisfying thepredetermined reproduced signal quality is determined. A recordingparameter for controlling heat of a rear edge, which is more apt to beaffected by heat than any other regions in the recording mark, isdetermined so as to satisfy the predetermined reproduced signal quality.This compensates the effect caused by the heat accumulated at the rearedge, thereby forming a recording mark capable of providing a goodreproduced signal quality.

This makes it possible to form a recording mark capable of surelyproviding a good reproduced signal quality while the number of recordingparameters to be used is reduced.

Also, in order to attain the object, the recording parameter settingdevice of the present invention is a recording parameter setting deviceconfigured to set a recording parameter for forming a recording mark onan information recording medium in accordance with recordinginformation, wherein the recording parameters include: (a) recordingparameters used for controlling heat of a front edge of the recordingmark, classified in accordance with at least recording mark lengths outof the recording information, and classified into the same group if therecording mark length is equal to or longer than a predeterminedrecording mark length; and (b) recording parameters used for controllingheat of a rear edge of the recording mark, classified in accordance withat least the recording mark lengths out of the recording information,and classified into more detailed groups than the recording parametersused for controlling the heat of the front edge if the recording marklength is equal to or longer than the predetermined recording marklength.

This allows the recording parameters for controlling the heat of therear edge of the recording mark to be classified into more detailedgroups than the recording parameters for controlling the heat of thefront edge of the recording mark. This reduces the number of recordingparameters as a whole, compared with a method of increasing the numberof classifications of the recording parameters for controlling the heatof both the front and rear edges. The rear edge of the recording mark ismore apt to be affected by heat than any other regions in the recordingmark. In view of this, the recording parameters for controlling the heatof the rear edge are classified into more detailed groups. This makes itpossible to control more strictly the heat of the rear edge, at whichthe forming process of the recording mark ends, and to compensate theeffect caused by the accumulated heat. As a result, a recording markcapable of providing a good reproduced signal quality can be formed.

This makes it possible to form a recording mark capable of surelyproviding a good reproduced signal quality while the number of recordingparameters to be used is reduced.

In order to attain the object, an information recording medium of thepresent invention is an information recording medium configured tocontain, in a predetermined region, a recording parameter for forming arecording mark in accordance with recording information, wherein therecording parameters include: (a) recording parameters used forcontrolling heat of a front edge of the recording mark, classified inaccordance with at least recording mark lengths out of the recordinginformation, and classified into the same group if the recording marklength is equal to or longer than a predetermined recording mark length;and (b) recording parameters used for controlling heat of a rear edge ofthe recording mark, classified in accordance with at least the recordingmark lengths out of the recording information, and classified into thesame group if the recording mark length is longer than the predeterminedrecording mark length.

With the invention, the recording parameters for controlling the heat ofat least the front edge of the recording mark are classified into thesame group if the recording mark length is equal to or longer than thepredetermined recording mark length. Also, with the invention, therecording parameters for controlling the heat of the rear edge areclassified into the same group if the recording mark length is longerthan the predetermined recording mark length. This reduces the number ofrecording parameters as a whole, compared with a method in which therecording parameters are classified into different groups for everyrecording mark length.

Also, this invention allows the recording parameters for controlling theheat of the rear edge of the recording mark to be classified into moredetailed groups than the recording parameters for controlling the heatof the front edge of the recording mark. This reduces the number ofrecording parameters as a whole, compared with a method of increasingthe number of classifications of the recording parameters forcontrolling the heat of both the front and rear edges.

This makes it possible to form a recording mark capable of surelyproviding a good reproduced signal quality while the number of recordingparameters to be used is reduced.

In order to attain the object, a recording parameter setting method ofthe present invention is a recording parameter setting method forsetting a recording parameter for forming a recording mark on aninformation recording medium in accordance with recording information,comprising: (i) a trial recording parameter setting step which inquires,in accordance with the recording information, a storage sectioncontaining recording parameters used for controlling heat of at least arear edge (at which a forming process of the recording mark ends) of therecording mark, classified in accordance with at least recording marklengths out of the recording information, and classified into the samegroup if the recording mark length is equal to or longer than apredetermined recording mark length, so as to set a trial recordingparameter for carrying out trial recording; and (ii) a reproduced signalquality judging step: which further classifies the recording parametersfor the recording mark length equal to or longer than the predeterminedrecording mark length into detailed groups and carries out trialrecording again if a reproduced signal obtained by the reproduction ofthe trial recording carried out in accordance with the trial recordingparameter does not satisfy a predetermined reproduced signal quality;and which sets the trial recording parameter as the recording parameterif the reproduced signal satisfies the predetermined reproduced signalquality.

The invention makes it possible to form a recording mark capable ofsurely providing a good reproduced signal quality while the number ofrecording parameters to be used is reduced.

Also, in order to attain the object, a recording parameter settingmethod of the present invention is a recording parameter setting methodfor setting a recording parameter for forming a recording mark on aninformation recording medium in accordance with recording information,comprising: (i) a first recording parameter classification step whichclassifies, in accordance with at least recording mark lengths out ofthe recording information, recording parameters used for controllingheat of a front edge of the recording mark and classifies the recordingparameters into the same group if the recording mark length is equal toor longer than a predetermined recording mark length; and (ii) a secondrecording parameter classification step which classifies, in accordancewith at least the recording mark lengths out of the recordinginformation, recording parameters used for controlling heat of a rearedge of the recording mark, and which further classifies the recordingparameters into more detailed groups than the recording parameters usedfor controlling the heat of the front edge if the recording mark lengthis equal to or longer than the predetermined recording mark length.

The foregoing invention makes it possible to form a recording markcapable of surely providing a good reproduced signal quality while thenumber of recording parameters to be used is reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a functional block diagram illustrating one of the embodimentsof a control section in an optical disc device in accordance with thepresent invention.

FIG. 2 is a block diagram illustrating one of the embodiments of theoptical disc device.

FIG. 3 is a perspective view of an optical disc on which information isrecorded by the optical disc device.

FIG. 4 is a timing chart illustrating a setting of a pulse sequencecorresponding to recording information.

FIG. 5 is a timing chart illustrating a pulse sequence and a recordingpulse parameter for forming recording marks whose lengths are 2T through9T.

FIG. 6 is a flow chart illustrating a flow of recording parametersetting operation in the present invention.

FIG. 7 is a view illustrating one of the embodiments of a look-up tablein accordance with the present invention.

FIG. 8 is a view illustrating one of the embodiments of a look-up tablein accordance with the present invention.

FIG. 9 is a view illustrating one of the embodiments of a look-up tablein accordance with the present invention.

FIG. 10 is a view illustrating one of the embodiments of a look-up tablein accordance with the present invention.

FIG. 11 is a view illustrating one of the embodiments of a look-up tablein accordance with the present invention.

FIG. 12 is a view illustrating a change in jitter related to a recordingparameter condition.

FIG. 13 is a timing chart illustrating one of the embodiments of a pulsesequence and a recording pulse parameter for forming recording markswhose lengths are 2T through 9T.

FIG. 14 is a timing chart illustrating one of the embodiments of a pulsesequence and a recording pulse parameter for forming recording markswhose lengths are 2T through 9T.

FIG. 15 is a view illustrating a change in jitter related to a recordingparameter condition in the present invention.

FIG. 16 (a) is a view illustrating one of the embodiments of a look-uptable recorded on an optical disc in the present invention.

FIG. 16 (b) is a view illustrating one of the embodiments of a look-uptable recorded on an optical disc in the present invention.

FIG. 17 is a view illustrating a look-up table in accordance with aconventional art.

FIG. 18 is a view illustrating a look-up table in accordance with aconventional art.

BEST MODE FOR CARRYING OUT THE INVENTION

One of the embodiments of the present invention is described below withreference to FIG. 1 through FIG. 16 (b).

Firstly, as an example of a recording/reproducing device of the presentembodiment, an optical disc device (recording/reproducing device) 1 isdescribed. As illustrated in FIG. 2, the optical disc device 1 of thepresent embodiment includes an optical head (optical pickup) 11, apickup 12, a pickup driving circuit 13, a laser driving circuit 14, areproducing circuit 15, and a control section 20. The pickup drivingcircuit 13, the laser driving circuit 14, and the reproducing circuit 15constitute a recording/reproducing circuit group 10. The optical discdevice 1 is a device for recording information on the optical disc 2 andreproducing information from the optical disc 2. The optical disc 2 maybe any optical disc such as a magneto-optical disc, and is not limitedto a particular kind.

The optical head 11 is included in the pickup 12. The optical head 11irradiates a light beam (i.e., a laser beam) onto the optical disc 2 soas to record/reproduce information. Also, the optical head 11 detectslight reflected from the optical disc 2 and outputs the result of thedetection to the reproducing circuit 15. The pickup 12, which includesthe optical head 11, records and reproduces data. The pickup 12 can bemoved in the direction of an optical axis and in a radial direction ofthe optical disc 2.

The pickup driving circuit 13 drives the pickup 12 in accordance with acontrol signal from the control section 20, and moves the pickup 12toward a track (not illustrated) of the optical disc 2, that is, in theradial direction and in the direction of the optical axis. The laserdriving circuit 14 controls an output of a light beam irradiated fromthe optical head 11. The reproducing circuit 15 converts the reflectedlight which is detected by the optical head 11 into a reproduced signal,and outputs the reproduced signal to the control section 20.

The control section 20 sets a recording parameter of a recording mark,which is information to be stored in the optical disc 2. Also, thecontrol section 20 moves the pickup 12 by using the pickup drivingcircuit 13, and causes the optical head 11 to irradiate a light beam byusing the laser driving circuit 14. In addition, the control section 20receives, from the reproducing circuit 15, the reproduced signal whichis obtained by the conversion of the reflected light detected by theoptical head 11. The control section 20 will be described in detaillater.

Next, with reference to FIG. 3, the optical disc 2 on which informationis recorded by the optical disc device 1 is described schematically. Theoptical disc 2 includes, as shown in FIG. 3, a setting region 41 and auser region 42. The setting region 41 is a region (i.e., a section) inwhich trial recording of information is carried out, and the user region42 is a section in which information desired by a user is to berecorded. Also, the setting region 41 is a region which stores a look-uptable described later.

Note that the position of the setting region 41 is not limited to theposition illustrated in FIG. 3. The setting region 41 may exist in anyposition within the radius of the optical disc 2. Also, a plurality ofsetting regions 41 may be provided.

Next, the following operation is briefly described: operation forrecording information on the optical disc 2 by using the optical discdevice 1; and operation for reproducing, by using the optical discdevice 1, information recorded on the optical disc 2.

The optical disc device 1 records information on the optical disc 2 suchthat: firstly, the control section 20 sets a recording parameter inaccordance with the recording information; secondly, the optical head 11irradiates a recording light beam (i.e., a light beam for recording)onto the setting region 41 on the optical disc 2, thereby recording theinformation in a track of the setting region 41 on the optical disc 2.The optical disc device 1 reproduces information recorded on the opticaldisc 2 such that: firstly, the control section 20 moves, by using thepickup driving circuit 13, the pickup 12 to a recorded section (on whichthe information is recorded) of either of the setting region 41 or theuser region 42, each of which is provided on the optical disc 2;secondly, the control section 20 causes, by using the laser drivingcircuit 14, the optical head 11 to irradiate a reproducing light beam(i.e., a light beam for reproducing) onto a track of a recorded section(on which the information is recorded) on the optical disc 2; and lightreflected from the track is detected by the optical head 11 and thenconverted into a reproduced signal by the reproducing circuit 15 andinputted to the control section 20. Thus, the optical disc device 1reproduces the information recorded in the track on the optical disc 2.The recording information here means binary digital data recorded on theoptical disc 2 (i.e., the information recording medium). The binarydigital data is expressed by (i) two states including a state where arecording mark is formed on the optical disc 2 (i.e., a mark) and astate where a recording mark is not formed on the optical disc 2 (i.e.,a space) and (ii) each length of the two states. That is, the followingsare specified in the recording information: (i) the two states includingthe state where a recording mark is formed on the optical disc 2 (i.e.,the mark) and the state where a recording mark is not formed on theoptical disc 2 (i.e., the space); and (ii) each length of the two states(each of (i) and (ii) is set in a recording parameter).

The optical disc device 1 in accordance with the present embodimentfirstly carries out recording (i.e., trial recording) on the settingregion 41 on the optical disc 2 as described above, and then sets arecording parameter by using the control section 20 in accordance with avalue of a reproduced signal obtained by reproduction of the informationrecorded in the trial recording. Then, the optical disc device 1 recordsthe information in a track on the user region 42 in accordance with therecording parameter thus set. Recording operation with respect to theuser region 42 after the optical disc device 1 sets the recordingparameter is similar to recording operation which is commonly known.Therefore, the detailed description of the recording operation withrespect to the user region 42 is omitted here. The recording parametersetting operation carried out by the control section 20 will bedescribed later in detail in the description of the control section 20.

Ahead of the detailed descriptions of the control section 20 and therecording parameter setting operation carried out by the control section20, a recording parameter is described with reference to FIG. 4 and FIG.5. The description given here is based on (1, 7) RLL (Run Length Limitedcode) as one of the examples of a modulation method. Note that themodulation method is not limited to the (1, 7) RLL in the presentembodiment. The (1, 7) RLL code is a code which limits a minimum valueand a maximum value of an inversion interval in magnetic digitalrecording and optical digital recording.

In the (1, 7) RLL modulation method, a shortest recording mark of 2T hasa pulse sequence of a recording pulse including a top section and a lastsection. A recording mark which is longer than the shortest recordingmark has a pulse sequence of a recording pulse including the topsection, the last section, and an intermediate section which is providedbetween the top section and the last section and whose length isdetermined in accordance with the mark length. This will be described indetail later. In other modulation methods, for example, the shortestrecording mark may be 3T (e.g., a DVD-RW). In this case, a shortestrecording mark may include a top section, an intermediate section, and alast section. In another case, a shortest recording mark may include atop section only (e.g., a DVD-R). The symbol “T” herein represents atime equivalent to one cycle of a clock. For example, a 3T recordingmark length indicates a recording region where a recording mark isformed in time equivalent to three cycles of the clock.

As illustrated in FIG. 4, a pulse sequence of a recording pulsecorresponding to recording information is set in the optical disc 2 inconsideration of a medium temperature distribution for carrying outrecording. FIG. 4 shows a recording pulse corresponding to recordinginformation, where the recording information is a recording mark lengthof 5T, for example. A pulse sequence of a recording pulse is expressedby time and recording pulse power. In FIG. 4, the horizontal axisindicates irradiation time, and the vertical axis indicates recordingpulse power.

As described above, a pulse sequence includes a top section, a lastsection, and an intermediate section. As illustrated in FIG. 4, the topsection here includes a top section rise position and a top pulse; thelast section here includes a last pulse, a last section fall position, acooling period, and a cooling end position; and the intermediate sectionhere includes an intermediate period provided between the top pulse andthe last pulse. As illustrated in FIG. 4, the pulse sequence is formedfrom recording power, space power, intermediate power, and bias(cooling) power. In the present embodiment, the recording power, thespace power, the intermediate power, and the bias (cooling) power form apulse sequence, and are termed “recording power parameter”. Theserecording power parameters are included in the foregoing recordingparameters. In FIG. 4, the recording power of the recording pulse of thetop section and the recording power of the recording pulse of the lastsection are identical to each other. However, the present invention isnot limited to this. The recording power of the top section and therecording power of the last section may be different from each other.Also, in FIG. 4, the smallest power is the bias (cooling) power, theintermediate power, the space power, and the recording power, in thisorder. However, the present invention is not limited to this. Note that,it is preferable that the recording power of the recording pulse ofeither of the top section or the last section has the highest value andthe cooling power has the lowest value.

FIG. 5 illustrates pulse sequences and recording pulse parameters forforming recording marks of recording mark lengths of 2T through 9T. FIG.5 shows the following example: each of the recording marks of therecording mark lengths of 2T and 3T includes a top pulse and a coolingperiod, and each of the recording marks of the recording mark lengths of4T or longer includes a top pulse, an intermediate period, a last pulse,and a cooling period. In FIG. 5, “dTtop” indicates a top section riseposition at which a top pulse starts; “Ttop” indicates the width of atop pulse; “dTe” indicates a cooling end position at which a coolingperiod in a last section ends; “Tlp” indicates the width of a lastpulse; and “dTlp” indicates a fall position of the last pulse (i.e., alast section fall position). Also, “dTlp” indicates, as well as the fallposition of the last pulse, a cooling start position at which a coolingperiod in a last section of the pulse sequence starts. Further, “dTe”indicates, as well as the cooling end position at which the coolingperiod in the last section ends, a start position of a space power “Ps”irradiation period, which subsequently starts following the coolingperiod. Each of “dTtop”, “dTe”, and “dTlp” is set in accordance withtime from a reference timing of a clock. Specifically, “dTtop” is set inaccordance with time based on a rise position of recording informationcorresponding to each recording mark length (i.e., a position at whichthe value changes from 0 to 1); and “dTe” and “dTlp” are set inaccordance with time based on a fall position of recording informationcorresponding to each recording mark length (i.e., a position at whichthe value changes from 1 to 0). At this time, the same reference is usedfor all the recording mark lengths. In FIG. 5, “dTtop” is set inaccordance with time based on the rise position of the recordinginformation as described above. However, “dTtop” may be set inaccordance with time based on a position that is shifted by apredetermined clock-interval from the rise position of the recordinginformation. Similarly, in FIG. 5, “dTe” and “dTlp” are set inaccordance with time based on the fall position of the recordinginformation as described above. However, “dTe” and “dTlp” may be set inaccordance with time based on a position that is shifted by apredetermined clock-interval from the fall position of the recordinginformation. Also, “dTe” and “dTlp” may have different amount ofshifting of the standard position from the fall position of therecording information. In the present embodiment, “dTtop”, “Ttop”,“dTe”, “Tlp”, and “dTlp”, each of which defines timing in a recordingpulse, are termed “recording pulse parameter”. These recording pulseparameters are included in the foregoing recording parameters.

In FIG. 5, “Ttop” defines the width of the top pulse. However, theperiod in which the top pulse is risen may also be expressed by settinga recording pulse parameter at the fall position of the top pulse.Similarly, “Tlp” defines the width of the last pulse. However, theperiod in which the last pulse is risen may also be expressed by settinga recording pulse parameter at the rise position of the last pulse.

Changing the value of a recording pulse parameter changes the shape of arecording mark to be formed. The shape of a front edge, at which aforming process of a recording mark starts, is changed by “dTtop” and“Ttop”, by which a top section is formed. That is, the parameters“dTtop” and “Ttop” out of the recording pulse parameters are capable ofcontrolling the heat of the front edge. Also, the shape of a rear edge,at which a forming process of a recording mark ends, is changed by“dTe”, “Tlp”, and “dTlp”, by which a last section is formed. That is,the parameters “dTe”, “Tlp”, and “dTlp” out of the recording pulseparameters are capable of controlling the heat of the rear edge.Further, changing the value of an intermediate power out of therecording power parameters changes the amount of heat accumulated at theintermediate section. That is, the intermediate power parameter out ofthe recording power parameters is capable of controlling the shape of arecording mark in a range between the front edge and the rear edge.

The values of the recording parameters including the foregoing recordingpower parameters and the recording pulse parameters are stored in thesetting region 41 in a form of a look-up table (i.e., recordingparameters). The look-up table is read out by the optical disc device 1,and is stored (i.e., recorded) in a storage section 3. The storagesection 3 may be any one of an information recording medium (such as amemory), a server, and the like. Also, the storage section 3 may beprovided in the optical disc device 1, or may be connected externally tothe optical disc device 1. The look-up table will be described in detaillater.

Next, the following gives the detail description of how the controlsection 20 in the optical disc device 1 sets a recording parameter.Firstly, with reference to FIG. 1, the outline of the arrangement of thecontrol section 20 is described. FIG. 1 is a functional block diagramillustrating the arrangement of the control section 20 of the presentembodiment.

As shown in FIG. 1, the control section 20 includes a recordingparameter setting section (i.e., a recording parameter setting device)21. The recording parameter setting section 21 carries out the followingfunctions of the control section 20: (i) the function for setting arecording parameter of a recording mark, which is information to berecorded on the optical disc 2; (ii) the function for causing, by usingthe laser driving circuit 14, the optical head 11 to irradiate a lightbeam; and (iii) the function for receiving, from the reproducing circuit15, a reproduced signal obtained by the conversion of reflected lightdetected by the optical head 11. The recording parameter setting section21 includes a recording information acquisition section 22, a trialrecording parameter setting section (i.e., trial recording parametersetting means) 23, a trial recording instruction section 24, areproduced signal acquisition section 25, a reproduced signal qualityjudging section (i.e., reproduced signal quality judging means) 26, anda recording instruction section 27. The recording parameter settingsection 21 carries out the above-mentioned functions by using thesesections.

The recording information acquisition section 22 acquires recordinginformation to be recorded on the optical disc 2. The recordinginformation may be acquired from any one of the followings: a controlsection which is upper-level than the control section 20, a memorystoring the recording information, a server storing the recordinginformation, and the like. Also, the acquisition source of the recordinginformation may be included in the optical disc device 1, or may beexternally connected to the optical disc device 1.

The trial recording parameter setting section 23 sets a trial recordingparameter for trial recording operation such that (i) the trialrecording parameter setting section 23 inquires the storage section 3 inaccordance with the recording information thus obtained by the recordinformation acquisition section 22 and (ii) the trial recordingparameter setting section 23 obtains, out of the recording parametersdefined in the look-up table in the storage section 3, a recordingparameter corresponding to the recording information. Also, the trialrecording parameter setting section 23 resets the trial recordingparameter when the trial recording parameter setting section 23receives, from the reproduced signal quality judging section 26(described later), a command to reset the trial recording parameter forthe trial recording operation (i.e., a trial recording parametermodification command). The resetting of the trial recording parameterwill be described later.

The trial recording instruction section 24 instructs the pickup drivingcircuit 13 and the laser driving circuit 14 to carry out the trialrecording on the setting region 41 on the optical disc 2 in accordancewith the trial recording parameter thus set by the trial recordingparameter setting section 23.

When the trial recording of the recording mark is carried out on thesetting region 41 on the optical disc 2 in accordance with theinstruction from the trial recording instruction section 24, areproduced signal is generated.

The reproduced signal acquisition section 25 acquires the reproducedsignal from the reproducing circuit 15.

The reproducing signal quality judging section 26 judges whether or notthe trial recording parameter used in the trial recording is good, inaccordance with the reproduced signal obtained by the reproduced signalacquisition section 25. This judgment depends on whether or not thereproduced signal obtained by the reproduced signal acquisition section25 satisfies a predetermined reproduced signal quality. When thereproduced signal satisfies the predetermined reproduced signal quality,the reproduced signal quality judging section 26 determines (i.e., sets)the trial recording parameter used in the trial recording as therecording parameter, and transmits the recording parameter to therecording instruction section 27. When the reproduced signal does notsatisfy the predetermined reproduced signal quality, the reproducedsignal quality judging section 26 judges whether or not the number ofclassifications in the look-up table looked up by the trial recordingparameter setting section 23 is equal to or greater than a predeterminedvalue. When the number of the classifications in the look-up table isnot equal to or greater than the predetermined value, the reproducedsignal quality judging section 26 transmits, to the trial recordingparameter setting section 23, a trial recording parameter modificationcommand to reset the trial recording parameter. At the same time, thereproduced signal quality judging section 26 resets the classificationin the look-up table stored in the storage section 3 so as to make theclassification more detailed. When the number of classifications in thelook-up table is equal to or greater than the predetermined value, thereproduced signal quality judging section 26 judges that an error occursin the recording parameter setting operation. Then, the reproducedsignal quality judging section 26 causes a display section (notillustrated) to display the error, and ends the recording parametersetting operation. The predetermined value will be described in detaillater. The predetermined reproduced signal quality herein means: areproduced signal quality which can be sufficiently compensated by anerror modification function of a recording/reproducing device (theoptical disc device 1 in the present embodiment); and a value which isset arbitrary in consideration of a quality fluctuation which occurs dueto mass production of a recording/reproducing device, an optical disc(the optical disc 2 in the present embodiment), and the like. For thereproduced signal quality, jitter, an error rate, or the like may beused. When every optical disc has different bottom-level specs injitter, an error rate, or the like, a bottom-level value prescribed bythe specs may be used as a predetermined reproduced signal quality.

The recording instruction section 27 instructs the pickup drivingcircuit 13 and the laser driving circuit 14 to carry out recordingoperation on the user region 42 on the optical disc 2, in accordancewith the recording parameter transmitted by the reproduced signalquality judging section 26.

The following description deals with the recording parameter settingoperation in the optical disc device 1 with reference to FIGS. 6 through11. FIG. 6 is a flow chart of the recording parameter setting operationin the present embodiment. FIG. 7 through FIG. 11 are a viewillustrating a look-up table in the present embodiment.

Firstly, in Step S1, the recording information acquisition section 22acquires recording information to be recorded on the optical disc 2.Secondly, in Step S2, the trial recording parameter setting section 23inquires the storage section 3 in accordance with the recordinginformation thus acquired by the recording information acquisitionsection 22, so as to set a trial recording parameter. Specifically, thetrial recording parameter setting section 23 looks up a look-up tablesuch as in FIG. 7 and FIG. 11 in accordance with the recordinginformation, obtains a recording parameter corresponding to therecording information, and then sets a trial recording parameter. FIG. 7shows a look-up table of “dTlp”, which is a recording pulse parameterand indicates a fall position of a last pulse. The look-up table of“dTlp” is used as a look-up table for controlling heat of a rear edge,at which a forming process of a recording mark ends. In the look-uptable in FIG. 7, recording mark lengths of 4T or longer are classifiedinto one group. When the recording mark length of the recordinginformation does not reach 4T, a recording parameter set by default isset as the recording parameter. When the recording mark length of therecording information is equal to or longer than 4T, a value (“b4” inFIG. 7) of a corresponding group in the look-up table is set as therecording parameter. For the default setting, for example, a value of“Ttop” or “dTlp” may be set in advance.

FIG. 11 show a look-up table of “dTtop”, which is a recording pulseparameter and indicates a top section rise position. The look-up tableof “dTtop” is used as a look-up table for controlling heat of a frontedge, at which a forming process of a recording mark starts. In FIG. 11,recording mark lengths are classified into three groups: 2T, 3T, and 4Tor longer. The number of classifications will not be changed in thetrial recording carried out later. Therefore, the number of recordingparameters for controlling the heat of the front edge will not increaseany more.

As described above, each of the look-up tables in FIG. 7 and FIG. 11 isrecorded on the setting region 41 on the disc. The optical disc device 1reads out the look-up table, and stores the look-up table in the storagesection 3. After that, the trial recording parameter setting section 23looks up the look-up table in the storage section 3 so as to set a trialrecording parameter. When “dTlp” is a fall position of a last pulse of arecording mark whose length is longer than 4T (i.e., 5T or longer), avalue (i.e., “b4”) for a recording mark length equal to 4T is set for“dTlp” by the trial recording parameter setting section 23. Also, when“dTtop” is a top section rise position of a recording mark whose lengthis longer than 4T (i.e., 5T or longer), a value (i.e., “c4”) for arecording mark length of 4T is set for “dTtop” by the trial recordingparameter setting section 23. That is, the trial recording parametersetting section 23 sets the same value for a recording mark length of 4Tand for a recording mark length of 5T or longer. This shortens theread-out time, compared with a method in which a plurality of parametersare respectively set for recording mark lengths of 4T through 9T and theplurality of parameters are read out. The trial recording parametersetting section 23 sets a certain value of the recording parameter incommon for recording marks lengths of 4T through 9T. When trialrecording is carried out, the trial recording parameter setting section23 gives a certain amount of change in common to the recording marklengths of 4T through 9T. That is, the value of the amount of changeused in trial recording of a recording mark length of 4T is commonlyused as the value of the amount of change used in trial recording ofrecording mark lengths of 4T through 9T.

In Step S3, the trial recording instruction section 24 instructs thepickup driving circuit 13 and the laser driving circuit 14 to carry outtrial recording on the setting region 41 on the optical disc 2 inaccordance with the trial recording parameter thus set by the trialrecording parameter setting section 23. Next, in Step S4, the pickupdriving circuit 13 and the laser driving circuit 14 cause the opticalhead 11 to record the information onto the setting region on the opticaldisc 2 in accordance with the trial recording parameter. Then, in StepS5, the optical head 11 reproduces the information, and a reproducedsignal is generated by the reproducing circuit 15.

In Step S6, the reproduced signal acquisition section 25 acquires thereproduced signal, and transmits the reproduced signal to the reproducedsignal quality judging section 26. In Step S7, the reproduced signalquality judging section 26 judges whether or not the reproduced signalacquired by the reproduced signal acquisition section 25 satisfies apredetermined reproduced signal quality. If the reproduced signalsatisfies the predetermined reproduced signal quality (i.e., “YES” inStep S7), the procedure proceeds to Step S8. If the reproduced signaldoes not satisfy the predetermined reproduced signal quality (i.e., “NO”in Step S7), the procedure proceeds to Step S9. Specifically, thejudgment whether or not the reproduced signal satisfies thepredetermined reproduced signal quality is carried out by observingwhether or not jitter (as the predetermined reproduced signal quality)satisfies a predetermined value (e.g., 6.5% or less).

In Step S8, the reproduced signal quality judging section 26 transmits,to the recording instruction section 27, the trial recording parameterused in the trial recording. This step sets (i.e., determines) therecording parameter for actually carrying out recording operation on theuser section 42 on the optical disc 2. The recording parameter settingoperation ends here.

In Step S9, the reproduced signal quality judging section 26 judgeswhether or not the number of classifications in the look-up table lookedup by the trial recording parameter setting section 23 is equal to orgreater than a predetermined value. If the number of classifications inthe look-up table is equal to or greater than the predetermined value(i.e., “YES” in Step S9), the procedure proceeds to Step S10. If thenumber of classifications in the look-up table is not equal to orgreater than the predetermined value (i.e., “NO” in Step S9), theprocedure proceeds to Step S11. The predetermined value is describedbelow. For example, in the look-up table in FIG. 7, the number ofclassifications is one. In the present embodiment, the maximum recordingmark length is 9T. When the recording mark lengths of 4T through 9T areclassified separately, the number of classifications in the look-uptable is six, which is the maximum value. In this case, in Step S9, whenthe reproduced signal quality judging section 26 judges that the numberof classifications in the look-up table looked up by the trial recordingparameter setting section 23 is seven, a contradiction occurs becausethe actual number of classifications in the look-up table in FIG. 7 issix at maximum. This means an error in the recording parameter settingoperation. Also, in Step S9, when the reproduced signal quality judgingsection 26 judges that the number of classifications in the look-uptable looked up by the trial recording parameter setting section 23 issix, the number of classifications cannot be increased any more becausethe number of classifications judged by the reproduced signal qualityjudging section 26 is equal to the maximum number of classifications inthe look-up table in FIG. 7. This also means an error in the recordingparameter setting operation. Therefore, the present embodiment uses, asthe foregoing predetermined value, the maximum number of classificationsin the look-up table looked up by the trial recording parameter settingsection 23. This makes it possible to detect an error in the recordingparameter setting operation. Resetting the trial recording parameterused in the trial recording changes the look-up table looked up by thetrial recording parameter setting section 23. The predetermined valuechanges in accordance with the maximum number of classifications in thelook-up table which is changed when the look-up table changes asdescribed above herein.

In Step S10, the reproduced signal quality judging section 26 causes adisplay section (not illustrated) to display an error so as to indicatethat the recording parameter setting operation has an error. At the sametime, the reproduced signal quality judging section 26 ends therecording parameter setting operation.

In Step S11, the reproduced signal quality judging section 26 transmits,to the trial recording parameter setting section 23, a trial recordingparameter modification command to reset the trial recording parameter.Also, the reproduced signal quality judging section 26 resets theclassification of the look-up table stored in the storage section 3 intomore detailed groups. Specifically, a look-up table in which recordingmark lengths of 4T or longer are classified into only one group ismodified to be a look-up table (as shown in FIG. 8) in which recordingmark lengths of 4T or longer are classified into two groups: 4T and 5Tor longer. Then, the look-up table thus modified is set in the trialrecording parameter setting section 23. This makes it possible to carryout the trial recording by separately controlling a setting value of atrial recording parameter of a recording mark length of 4T from asetting value of a trial recording parameter of a recording mark lengthof 5T or longer. After the trial recording parameter setting section 23receives the trial recording parameter modification command, the trialrecording parameter setting section 23 inquires the storage section 3again. Then, the trial recording parameter setting section 23 obtains arecording parameter corresponding to the recording information fromamong the recording parameters defined in the look-up table in FIG. 8,so as to reset the trial recording parameter used in the trial recordingoperation. Here, the same value is set for recording mark lengths of 5Tthrough 9T. Also, the same amount of change is given to recording marklengths of 5T through 9T when the trial recording is carried out. Thatis, the value for a recording mark length of 5T is used commonly forrecording mark lengths of 5T through 9T. After the look-up table ischanged, the procedure returns to Step S2 and carries out the operationflow thereafter. Every time the procedure returns to Step S2 and theoperation flow is carried out again, the classification of the look-uptable stored in the storage section 3 is reset into more detailed groupsas described above. Specifically, after the look-up table illustrated inFIG. 8 is used, the look-up table classified to have three groups of 4T,5T, and 6T or longer (as illustrated in FIG. 9) is used. Further, afterthe look-up table illustrated in FIG. 9 is used, the look-up tableclassified to have four groups of 4T, 5T, 6T, and 7T or longer (asillustrated in FIG. 10) is used. Thus, the classification of the look-uptable is reset into more detailed groups by stages.

In the present embodiment, recording mark lengths of 4T or longer (i.e.,a predetermined recording mark length or longer) are classified into thesame group both in (i) a look-up table for controlling heat of a frontedge and (ii) a look-up table for controlling heat of a rear edge, bothof the look-up tables of (i) and (ii) being stored in the storagesection 3 at the time of starting the trial recording operation.However, the present invention is not limited to this. For example, outof the look-up table for controlling heat of a front edge and thelook-up table for controlling heat of a rear edge each of which isstored in the storage section 3 at the time of starting the trialrecording operation, it is preferable that the look-up table forcontrolling heat of a rear edge is classified to have more detailedgroups than the look-up table for controlling heat of a front edge.

Also, out of the look-up table for controlling heat of a front edge andthe look-up table for controlling heat of a rear edge, the look-up tablefor controlling heat of a rear edge may be recorded on the settingregion 41 on the optical disc 2 as a table classified to have moredetailed groups than the look-up table for controlling heat of a frontedge. In this case, when the look-up table is read out by the opticaldisc device 1 and stored (i.e., recorded) in the storage section 3, thelook-up table for controlling heat of a rear edge (out of the look-uptable for controlling heat of a front edge and the look-up table forcontrolling heat of a rear edge each of which is stored in the storagesection 3 at the time of starting the trial recording operation) isclassified to have more detailed groups than the look-up table forcontrolling heat of a front edge. That is, the following look-up tablesare included: (i) the look-up table for controlling heat of a frontedge, in which look-up table recording marks whose lengths are equal toor longer than a predetermined recording mark length are classified intothe same group; (ii) the look-up table for controlling heat of a rearedge, in which look-up table recording marks whose lengths are longerthan the predetermined recording mark length is classified into the samegroup (i.e., a recording mark whose length is equal to the predeterminedrecording mark length and a recording mark whose length is longer thanthe predetermined recording mark length are separated and classifiedinto different groups).

This allows the recording parameters for controlling heat of a rear edgeof a recording mark to be classified into more detailed groups than therecording parameters for controlling heat of a front edge of a recordingmark. Also, this reduces the number of recording parameters, comparedwith a method in which the recording parameters of both of a front edgeand a rear edge are classified into the increased number of groups. Arear edge of a recording mark is more apt to be affected by heat thanany other regions in the recording mark. Therefore, classifying alook-up table for controlling heat of a rear edge into more detailedgroups allows to more strictly control heat of a rear edge, at which aforming process of a recording mark ends. This compensates the effectcaused by accumulated heat, thereby forming a recording mark capable ofproviding a good reproduced signal quality.

The present embodiment is arranged such that a look-up table stored inthe storage section 3 is set to have more detailed groups when a trialrecording parameter is reset. However, the present invention is notlimited to this. For example, the following is also possible: Thestorage section 3 stores, in advance, a plurality of look-up tableshaving different number of classifications (e.g., the storage section 3stores, in advance, all of the look-up tables illustrated in FIG. 7,FIG. 8, FIG. 9, and FIG. 10); then, the trial recording parametersetting section 23 switches the look-up table to look up to anotherlook-up table when the trial recording parameter is reset.

For example, there is a case where the look-up table illustrated in FIG.10 is used as a look-up table of a recording parameter which isconclusively determined for a last pulse fall position “dTlp”. In thiscase, “dTlp” (i.e., a recording parameter for controlling heat of a rearedge of a recording mark) is set so that recording mark lengths of 4T orlonger are classified into groups of 4T, 5T, 6T, and 7T or longer asillustrated in FIG. 10. On the other hand, “dTtop” (i.e., a recordingparameter for controlling heat of a front edge of a recording mark) isnot reset by trial recording. Therefore, “dTtop” maintains the settingin Step S2 so that recording mark lengths are classified into threegroups of 2T, 3T, and 4T or longer as illustrated in FIG. 11.

When a look-up table is recorded on the setting region 41 on the opticaldisc 2, a value corresponding to a recording mark length is recordedfor, for example, the recording pulse parameters “dTtop” and “dTlp”.Specifically, the values for the recording pulse parameters “dTtop” and“dTlp” as illustrated in FIG. 16 (a) and FIG. 16 (b) are recorded on thesetting region 41.

As is clear from FIG. 16 (a) and FIG. 16 (b), the recording pulseparameter “dTtop” is classified and allocated to three regions of 2T,3T, and 4T or longer; the recording pulse parameter “dTlp” is classifiedand allocated to four regions of 2T, 3T, 4T, and 5T or longer. That is,the regions for storing the values of the recording pulse parameter“dTtop” are allocated in accordance with the recording mark length, andone region is allocated for storing the value of the recording pulseparameter for a recording mark length equal to or longer than apredetermined recording mark length (i.e., 4T or longer in FIG. 16 (a)).Also, the regions for storing the values of the recording pulseparameter “dTlp” are allocated in accordance with the recording marklength, and one region is allocated for storing the value of therecording pulse parameter for a recording mark length equal to or longerthan a predetermined recording mark length (i.e., 5T or longer in FIG.16 (b)).

As described above, in a case where a look-up table is recorded on thesetting region 41 on the optical disc 2, a look-up table for controllingheat of a rear edge so as to form the rear edge is classified to havemore detailed groups than a look-up table for controlling heat of afront edge so as to form the front edge. That is, an operation effect ofthe present invention is attained by reading out a look-up table fromthe setting region 41 on the optical disc 2.

Note that the value in a look-up table to be recorded on the settingregion 41 on the optical disc 2 may be a value that is recorded by theforegoing trial writing, or may be a value that is recorded aspre-stored information when various kinds of settings are carried outbefore shipment.

Next, an operation effect of the present invention is described withreference to FIG. 12. FIG. 12 is a view illustrating a correlationbetween a classification level of a look-up table and jitter in areproduced signal generated by a recording mark.

In Condition 1, a recording parameter of a last pulse fall position“dTlp” uses the look-up table in FIG. 7. (In the look-up table in FIG.7, recording parameters are classified into one group for a recordingmark length of 4T or longer.) In Condition 2, a recording parameter of alast pulse fall position “dTlp” uses the look-up table in FIG. 8. (Inthe look-up table in FIG. 8, recording parameters are classified intotwo groups, a group for a recording mark length of 4T and a group for arecording mark length of 5T or longer.) In Condition 3, a recordingparameter of a last pulse fall position “dTlp” uses the look-up table inFIG. 9. (In the look-up table in FIG. 9, recording parameters areclassified into three groups, a group for a recording mark length of 4T,a group for a recording mark length of 5T, and a group for a recordingmark length of 6T or longer.) In Condition 4, a recording parameter of alast pulse fall position “dTlp” uses the look-up table in FIG. 10. (Inthe look-up table in FIG. 10, recording parameters are classified intofour groups, a group for a recording mark length of 4T, a group for arecording mark length of 5T, a group for a recording mark length of 6T,and a group for a recording mark length of 7T or longer.) For example,when a predetermined reproduced signal quality is “jitter is 6.5% orless”, as is clear from FIG. 12, only Condition 4 can satisfy thepredetermined reproduced signal quality. That is, if recording marklengths are classified into too small number of groups so as to reducethe number of recording parameters, some conditions (such as Condition1, Condition 2, and Condition 3, in this case) cannot satisfy thepredetermined reproduced signal quality. In view of this, in the presentinvention, when the look-up table of Condition 1 cannot satisfy thepredetermined reproduced signal quality, the look-up table of Condition2 is used. Thus, a look-up table can be reset and classified minutely tohave more detailed groups until the predetermined reproduced signalquality is satisfied.

Note that the predetermined reproduced signal quality is not limited to“jitter is 6.5% or less”. The predetermined reproduced signal qualityherein means a level where an error in a reproduced signal can becorrected by the optical disc device 1. The predetermined reproducedsignal quality only needs to be capable of ensuring allowance for aquality fluctuation in the optical disc device 1 or the optical disc 2which occurs due to mass production or the other reasons. When thepredetermined reproduced signal quality is, for example, “jitter is 7%or less”, as is clear from FIG. 12, Conditions 2, 3, and 4 satisfy thepredetermined reproduced signal quality.

Next, an operation effect of the present invention is described withreference to FIG. 15. FIG. 15 is a view illustrating a correlationbetween a relative position of “dTlp” and jitter in a reproduced signalgenerated by a recording mark, the correlation being observed when bothof the following conditions are satisfied: (i) a recording parameter ofa last pulse fall position “dTlp” adopts the look-up table in FIG. 8 (inwhich recording pulse parameters are classified into two groups, a groupfor a recording mark length of 4T and a group for a recording marklength of 5T or longer); (ii) the position of “dTlp” of a recording markwhose length is equal to or longer than 5T shifts in an earlierdirection of a time axis (i.e., in an opposite direction to a timeproceeding direction) relative to the position of “dTlp” of a recordingmark whose length is equal to 4T. In this condition, the position of“dTlp” of the recording mark whose length is equal to or longer than 5Tis shifted to the left in FIG. 4 and FIG. 5 because the time proceedingdirection is represented by the direction from the left to the right inFIG. 4 and FIG. 5. A value of “dTlp” is set in accordance with timebased on a fall position of recording information corresponding to arecording mark length. A clock interval “T” herein is approximately 3.8ns, and the position of “dTlp” is shifted (i.e., moved) in every T/16.As illustrated in FIG. 15, when the position of “dTlp” of the recordingmark whose length is equal to or longer than 5T is moved, based on afall position of recording information, in an earlier direction of atime axis (i.e., in an opposite direction to a time proceedingdirection) relative to the position of “dTlp” of the recording markwhose length is equal to 4T, the jitter becomes preferable once and thenbecomes worse gradually (specifically, the jitter gradually becomespreferable before the relative position reaches “−3”, and the jittergradually becomes worse when the relative position reaches and exceeds“−3”). When “dTlp” is shifted, the value of the last pulse width “Tlp”is not changed. Therefore, along with the shift of “dTlp”, the riseposition of “Tlp” approaches the fall position of the top pulse width“Ttop”. As far as the fall position of “Ttop” does not overlap with therise position of “Tlp”, “dTlp” of the recording mark whose length isequal to or longer than 5T can be shifted in an opposite direction to atime proceeding direction.

The above-mentioned change in jitter is caused by the reason describedbelow. Increasing a recording mark length elongates an intermediateperiod between a top pulse and a last pulse. This increases heataccumulated at a rear edge of a recording mark. In view of this, theposition of “dTlp” of a recording mark whose length is equal to orlonger than 5T (i.e., a long recording mark length) is shifted in anearlier direction so that the intermediate period is shortened and theheat accumulated at the rear edge is reduced. This makes the jitter morepreferable than a case where the intermediate period is not shortened.However, if the position of “dTlp” is shifted in an earlier directionlargely, the intermediate period will become too short to obtainsufficient heat for forming a rear edge of a recording mark. This makesthe jitter worse. As illustrated in FIG. 15, the jitter becomes 7.0% orless, which is preferable, when the relative position of “dTlp” of arecording mark whose length is equal to or longer than 5T is within therange from −T/16 to −5T/16 (“+” herein represents a later direction of atime axis (i.e., a time proceeding direction)). Here, the relativeposition of “dTlp” of a recording mark whose length is equal to orlonger than 5T is determined relative to “dTlp” of a recording markwhose length is equal to 4T.

As described above, such a look-up table is included that defines arecording parameter for controlling heat of at least a rear edge of arecording mark. The look-up table is classified in accordance with atleast mark lengths out of the recording information. In the look-uptable, the mark lengths equal to or longer than a predetermined marklength are classified into the same group. Trial recording is carriedout by using a trial recording parameter which is set in accordance withthe look-up table, and then the trial recording is reproduced. If thetrial recording does not satisfy a predetermined reproduced signalquality, the look-up table for the mark lengths equal to or longer thanthe predetermined mark length is further classified into more detailedgroups in accordance with the mark length. After that, trial recordingis carried out and then reproduced, so that a look-up table whichsatisfies the predetermined reproduced signal quality is determined.This reduces, as much as possible, the number of recording parameters tobe used, and controls heat of a rear edge at which a forming process ofa recording mark ends. This compensates an effect caused by accumulatedheat, thereby forming a recording mark capable of providing a goodreproduced signal quality (i.e., a recording mark satisfying thepredetermined reproduced signal quality).

A rear edge of a recording mark is more apt to be affected by heat thanany other regions in the recording mark such as a front edge. Therefore,when a recording mark equal to or longer than a predetermined recordingmark length is formed, simply controlling heat of a rear edge forms arecording mark capable of providing a good reproduced signal quality.That is, setting a recording parameter for controlling heat of at leasta rear edge in accordance with the present invention makes it possibleto form a recording mark capable of surely providing a good reproducedsignal quality.

In an arrangement where a look-up table fixed in advance is used, when arecording condition of a track on the optical disc 2 changes along withthe lapse of time, the look-up table cannot be changed accordingly so asto suit the change in the recording condition of the track. This mayunable to form a recording mark capable of providing a good reproducedsignal quality (i.e., a recording mark satisfying the predeterminedreproduced signal quality) in a case where the recording condition ofthe track changes. In view of this, the present invention has anarrangement where a look-up table is further classified depending on theresult of trial recording. Therefore, even when the recording conditionof the track on the optical disc 2 changes along with the lapse of time,the look-up table can be classified again so as to suit the change inthe recording condition of the track. That is, even when the recordingcondition of the track changes along with the lapse of time, a recordingmark capable of providing a good reproduced signal quality (i.e., arecording mark satisfying the predetermined reproduced signal quality)can be formed.

The arrangement described below is also possible. After a look-up tableof a recording parameter is set, the look-up table is recorded on thesetting region 41 on the optical disc 2. When another recordingoperation is carried out later, the look-up table recorded on thesetting region 41 is read out by the optical disc device 1, and thelook-up table thus read out is used again so as to set a recordingparameter. For example, when the look-up table in FIG. 10 is determinedas a look-up table of a recording parameter of a last pulse fallposition “dTlp”, information indicative of this is recorded on thesetting region 41 on the optical disc 2. This allows the optical discdevice 1 to read out, from the setting region 41, the informationcontained in the look-up table in FIG. 10, and to use the informationfor the purpose of setting a recording parameter “dTlp” when anotherrecording operation is carried out later.

With the foregoing arrangement, after a look-up table of a recordingparameter is set in advance by carrying out trial recording, the look-uptable can be used as a look-up table of a trial recording parameter inanother recording operation. This makes it possible to reduce the numberof trial recording carried out repeatedly until a recording parameter isdetermined. In addition, this eliminates the necessity of adding a newrecording device such as a memory. This is because the setting region 41on the optical disc 2 stores a look-up table of a recording parameterafter the look-up table is set.

In the present embodiment, a recording parameter is used in a form of atable (i.e., a look-up table). However, the present invention is notlimited to this. Recording parameters may be gathered into a group andstored in a storage section.

The classification in the look-up table of the present embodiment startsfrom a mark having a shorter length and is carried out in steps.However, the present invention is not limited to this, although arecording mark having a shorter length appears more frequently in datato be recorded on the user region 42. In trial recording, the data to berecorded on the user region 42 is not necessarily used as it is. Usingdata which is randomly selected gives an advantage such that a goodreproduced signal quality can be achieved easily when recording marksare classified in steps from a recording mark having a shorter length.Also, classifying recording mark lengths in steps from a recording markhaving a shorter length allows the number of classifications ofrecording parameters to be a number just needed to satisfy apredetermined reproduced signal quality. That is, this gives anadvantage such that the number of recording parameters in a look-uptable is easily set to a number just needed to satisfy a predeterminedreproduced signal quality.

In the present embodiment, a recording mark length is used as recordinginformation to be classified in a look-up table. However, the presentinvention is not limited to this. For example, both of a recording marklength and a space length may be classified as recording information ina look-up table. In this case, if the classification of a space lengthis not changed and only the classification of a recording mark length ischanged, the number of recording parameters can be reduced as in thepresent embodiment.

In the present embodiment, a last pulse fall position “dTlp” isdescribed as one of the examples of a look-up table. However, thepresent invention may use a look-up table of “Tlp” (representing a lastpulse width) or “dTe” (representing a cooling end position at which acooling period ends) instead of “dTlp” so as to obtain a similar effect.This is because heat of a rear edge of a recording mark can also becontrolled by using either of the look-up table of “Tlp” or “dTe”. In apulse sequence in FIG. 5, two pulses, a top pulse and a last pulse, aregenerated when a recording mark length is equal to or longer than 4T. Inaddition to the pulse sequence in FIG. 5, examples of the pulse sequencemay encompass a pulse sequence in FIG. 13 and a pulse sequence in FIG.14. In the pulse sequence in FIG. 13, intermediate power Pm andrecording power Pw are set to be equal to each other, so that arecording mark is formed from one recording pulse. In the pulse sequencein FIG. 14, recording power Pw of a last pulse and intermediate power Pmare set to be equal to each other. The pulse sequences in FIG. 13 andFIG. 14 do not have “Tlp”, which represents a last pulse width. Insteadof “Tlp”, a last pulse fall position “dTlp” (illustrated in FIG. 13 andFIG. 14) may be used. That is, when a recording medium which generatesthe pulse sequence illustrated in FIG. 13 or FIG. 14 is used, a look-uptable of the last pulse fall position “dTlp” may be used. In this case,in FIG. 13, the position of “dTlp” may be shifted in an oppositedirection to a time proceeding direction as far as the positions of“dTtop” and “dTlp” do not overlap with each other. Also, in FIG. 14, theposition of “dTlp” may be shifted in an opposite direction to a timeproceeding direction as far as the fall position of “Ttop” and theposition of “dTlp” do not overlap with each other.

In the present embodiment, a top section rise position “dTtop” is usedas a recording parameter for controlling heat of a front edge. However,the present invention is not limited to this. A top pulse width “Ttop”may be used as a recording parameter instead of “dTtop”.

Also, the present embodiment has an arrangement where a recordingparameter for controlling heat of a front edge is not reset by trialrecording. However, the present invention is not limited to this. Forexample, the present invention may have an arrangement where a recordingparameter for controlling heat of a front edge is reset by trialrecording, as well as a recording parameter for controlling heat of arear edge. In this case, the recording parameter for controlling theheat of the front edge may be reset in a similar manner to the manner inwhich the recording parameter for controlling the heat of the rear edgeis reset.

In the present embodiment, the following two steps are carried out inthe recording parameter setting section 21: (i) a step for classifyingrecording parameters used for controlling heat of a front edge into thesame group if the recording mark length is equal to or longer than apredetermined recording mark length (a first step); (ii) a step forclassifying, in accordance with at least recording mark lengths out ofthe recording information, recording parameters used for controllingheat of a rear edge and further classifying the recording parametersinto more detailed groups than the recording parameters used forcontrolling the heat of the front edge if the recording mark length isequal to or longer than the predetermined recording mark length (asecond step). However, the present invention may have an arrangementwhich uses different means from these steps, provided that the means isequivalent to each of the steps (i.e., the first step and the secondstep).

In the present embodiment, recording mark lengths of 4T or longer areclassified into the same group in the look-up table used in the firsttrial recording. However, the present invention is not limited to this.The value of the recording mark length at which the recording marks areclassified into the same group may be any positive integral numberprovided that the number is equal to or greater than the value of apredetermined recording mark length. The description “equal to orgreater than the value of the predetermined recording mark length”herein indicates a range of the recording mark length in which a rearedge is supposed not to be affected by heat accumulated at a front edgeof a recording mark, that is, in which the recording parameter of therear edge is supposed to be controlled separately from the recordingparameter of the front edge. The predetermined recording mark length isarbitrary set depending on the type of an information recording medium(i.e., the optical disc 2 in the present embodiment).

In the present embodiment, jitter is used as an example for judging areproduced signal quality of trial recording. However, the presentinvention is not limited to this. For example, an error rate or the likemay be used for judging a reproduced signal quality. Any index may beused as far as the index can judge the reproduced signal quality oftrial recording.

The present embodiment uses (1, 7) RLL code as a run-length limitationcode of d=1. However, the present invention is not limited to this.Other modulation methods or other codes may be used.

The present embodiment uses the optical disc device which uses a lightmodulation recording method. However, the present invention is notlimited to this. An optical disc device which uses a magneto-opticalmodulation method may be used as an alternative. Further, the presentembodiment uses the optical disc device 1 as an example of arecording/reproducing device. However, the present invention is notlimited to this. The device only needs to record information by heatingthe surface of an information recording medium so as to change thephysical characteristics of the information recording medium. Forexample, a magnetic recording device or a magneto-optical disc devicemay be used as well as the optical disc device 1.

The sections and the processing steps included in the recordingparameter setting section 21 of the present embodiment can be realizedby the following: arithmetic means (such as a CPU) for executing aprogram stored in storage means (such as a ROM (Read Only Memory) or aRAM) and controlling input means (such as a keyboard), output means(such as a display), or communication means (such as an interfacecircuit). Therefore, when a computer including the foregoing means readsout the program stored in a recording medium and executes the program,various kinds of functions and processes to be carried out by therecording parameter setting section 21 of the present embodiment can berealized. Also, the various kinds of functions and processes can berealized on a desired computer by storing the program in a removablerecording medium.

The recording medium may be a program medium such as: a memory (notillustrated) such as a ROM for carrying out a process by using amicrocomputer; and a program medium which is readable when a recordingmedium is inserted into a program reading device (not illustrated)provided as an external storage device.

In any case, it is preferable that the program to be stored is accessedand executed by a microprocessor. Further, it is preferable that theprogram is read out and downloaded to a program storage area in themicrocomputer and then is executed. A program for downloading should bestored in advance in a main device including the microcomputer.

The program medium may be a storage medium which is removable from abody and which supports a program in a fixed manner. More specifically,examples of the storage medium may encompass: tape such as magnetic tapeand cassette tape; a magnetic disc such as a flexible disc and a harddisc; a disc such as a CD, MO, MD, and DVD; a card such as an IC card(including a memory card); and a semi-conductor memory such as a maskROM, an EPROM (Erasable Programmable Read Only Memory), an EEPROM(Electrically Erasable Programmable Read Only Memory), and a flash ROM.

In a system arrangement where a communication network (including theInternet) can be connected, it is preferable to have a storage mediumwhich supports a program in a flowing manner such as a manner in whichthe program is downloaded from the communication network.

Further, when a program downloaded from the communication network asdescribed above is used, it is preferable that a program for downloadingis stored in a main device in advance or is installed from anotherstorage medium.

With the present invention, the process of determining a recordingparameter which satisfies a predetermined reproduced signal quality iscarried out while the number of classifications of recording parametersis being increased. As a result, the number of classifications ofrecording parameters at the time when the recording parameter satisfyingthe predetermined reproduced signal quality is determined is furtherreduced. Also, a recording parameter for controlling heat of at least arear edge is determined so that the predetermined reproduced signalquality is satisfied. This compensates an effect caused by the heataccumulated at the rear edge, thereby forming a recording mark capableof providing a good reproduced signal quality. That is, the followingeffect is attained: a recording mark capable of surely providing a goodreproduced signal quality can be formed while the number of recordingparameters to be used is kept small.

A recording parameter setting device of the present invention is arecording parameter setting device configured to set a recordingparameter for forming a recording mark on an information recordingmedium in accordance with recording information, comprising: (i) trialrecording parameter setting means configured to inquire, in accordancewith the recording information, a storage section containing recordingparameters used for controlling heat of recording marks, and to set atrial recording parameter for carrying out trial recording, wherein (a)the recording parameters are used for controlling heat of at least rearedges of the recording marks at which rear edges a forming process ofthe recording marks ends, (b) the recording parameters are classified inaccordance with at least recording mark lengths out of the recordinginformation, and (c) recording parameters of a predetermined recordingmark length or longer are classified into a same group; and (ii)reproduced signal quality judging means configured to further classifythe recording parameters of the predetermined recording mark length orlonger into more detailed groups and to cause to carry out the trialrecording again if a reproduced signal obtained by reproduction of thetrial recording carried out in accordance with the trial recordingparameter does not satisfy a predetermined reproduced signal quality,and configured to set the trial recording parameter as the recordingparameter if the reproduced signal satisfies the predeterminedreproduced signal quality.

Also, in the recording parameter setting device of the presentinvention, it is preferable that the reproduced signal quality judgingmeans further classifies the recording parameters of the predeterminedrecording mark length or longer into (a) a group for the recording marklength which is equal to the predetermined recording mark length and (b)another group for the recording mark length which is longer than thepredetermined recording mark length, if the reproduced signal does notsatisfy the predetermined reproduced signal quality.

Thus, the process of determining the recording parameter which satisfiesthe predetermined reproduced signal quality is carried out while thenumber of classifications of recording parameters is increased by one.As a result, the number of classifications of recording parameters atthe time when the recording parameter satisfying the predeterminedreproduced signal quality is determined becomes a number just needed tosurely satisfy the predetermined reproduced signal quality. This makesit possible to form a recording mark capable of surely obtaining a goodreproduced signal quality while the number of recording parameters to beused is reduced.

Also, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameter is a lastsection fall position of a pulse sequence for forming the recordingmark.

Setting the last section fall position of the pulse sequence for formingthe recording mark as the recording parameter makes it possible to forma recording mark capable of surely providing a good reproduced signalquality while the number of recording parameters to be used is reduced.

Further, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameter is a last pulsewidth of a pulse sequence for forming the recording mark.

Setting the last pulse width of the pulse sequence for forming therecording mark as the recording parameter makes it possible to form arecording mark capable of surely providing a good reproduced signalquality while the number of recording parameters to be used is reduced.

In addition, it is preferable that the recording parameter settingdevice of the present invention is a recording parameter setting deviceconfigured to set a recording parameter for forming a recording mark onan information recording medium in accordance with recordinginformation, wherein the recording parameters include: (a) recordingparameters used for controlling heat of a front edge of the recordingmark, classified in accordance with at least recording mark lengths outof the recording information, and classified into the same group if therecording mark length is equal to or longer than a predeterminedrecording mark length; and (b) recording parameters used for controllingheat of a rear edge of the recording mark, classified in accordance withat least the recording mark lengths out of the recording information,and classified into more detailed groups than the recording parametersused for controlling the heat of the front edge if the recording marklength is equal to or longer than the predetermined recording marklength.

Also, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameter for controllingthe heat of the rear edge of the recording mark is a last section fallposition of a pulse sequence for forming the recording mark.

Setting the last section fall position of the pulse sequence for formingthe recording mark as the recording parameter for controlling the heatof the rear edge makes it possible to form a recording mark capable ofsurely providing a good reproduced signal quality while the number ofrecording parameters to be used is reduced.

Further, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameter for controllingthe heat of the rear edge of the recording mark is a last pulse width ofa pulse sequence for forming the recording mark.

Setting the last pulse width of the pulse sequence for forming therecording mark as the recording parameter for controlling the heat ofthe rear edge makes it possible to form a recording mark capable ofsurely providing a good reproduced signal quality while the number ofrecording parameters to be used is reduced.

In addition, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameter for controllingthe heat of the rear edge of the recording mark is a cooling endposition at which a cooling period ends in a pulse sequence for formingthe recording mark.

Setting the cooling end position at which the cooling period ends in thepulse sequence for forming the recording mark as the recording parameterfor controlling the heat of the rear edge makes it possible to form arecording mark capable of surely providing a good reproduced signalquality while the number of recording parameters to be used is reduced.

Also, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameter for controllingthe heat of the front edge of the recording mark is a top section riseposition of a pulse sequence for forming the recording mark.

Setting the top section rise position of the pulse sequence for formingthe recording mark as the recording parameter for controlling the heatof the rear edge makes it possible to form a recording mark capable ofsurely providing a good reproduced signal quality while the number ofrecording parameters to be used is reduced.

Further, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameter for controllingthe heat of the front edge of the recording mark is a top pulse width ofa pulse sequence for forming the recording mark.

Setting the top pulse width of the pulse sequence for forming therecording mark as the recording parameter for controlling the heat ofthe front edge makes it possible to form a recording mark capable ofsurely providing a good reproduced signal quality while the number ofrecording parameters to be used is reduced.

Also, in the recording parameter setting device of the presentinvention, it is preferable that the recording parameters forcontrolling the heat of the rear edge of the recording mark areclassified into (a) a group for the recording mark length which is equalto the predetermined recording mark length and (b) another group for therecording mark length which is longer than the predetermined recordingmark length, if the recording mark length is equal to or longer than thepredetermined recording mark length.

That is, the number of classifications of recording parameters forcontrolling the heat of the rear edge of the recording mark is increasedby one from the number of classifications of recording parameters forcontrolling the heat of the front edge of the recording mark. This makesit possible to form a recording mark capable of surely providing a goodreproduced signal quality while the number of recording parameters to beused is reduced.

Also, in the recording parameter setting device of the presentinvention, it is preferable: that the recording parameters forcontrolling the heat of the rear edge of the recording mark areclassified into (a) the group for the recording mark length which isequal to the predetermined recording mark length and (b) the anothergroup for the recording mark length which is longer than thepredetermined recording mark length, if the recording mark length isequal to or longer than the predetermined recording mark length; andthat a value set for the recording parameter of the recording marklength which is longer than the predetermined recording mark length isdifferent from a value set for the recording parameter of the recordingmark length which is equal to the predetermined recording mark length.

As described above, the value set for the recording parameter of therecording mark length which is longer than the predetermined recordingmark length is different from the value set for the recording parameterof the recording mark length which is equal to the predeterminedrecording mark length. As a result, even when the recording mark lengthwhich is longer than the predetermined recording mark length elongatesso much that the jitter becomes deteriorated, the amount of heataccumulated at the rear edge is reduced by setting the recordingparameter of the recording mark length which is longer than thepredetermined recording mark length separately from the recordingparameter of the recording mark length which is equal to thepredetermined recording mark length. This makes it possible to form arecording mark capable of surely providing a good reproduced signalquality while the number of recording parameters to be used is reduced.

Further, in the recording parameter setting device of the presentinvention, it is preferable: that the recording parameter forcontrolling the heat of the rear edge of the recording mark is a lastsection fall position of a pulse sequence for forming the recordingmark; and that the last section fall position of the pulse sequence forforming the recording mark whose length is longer than the predeterminedrecording mark length is set so as to be shifted, relative to the lastsection fall position of the pulse sequence for forming the recordingmark whose length is equal to the predetermined recording mark length,in an opposite direction to a time proceeding direction (along a timeaxis) based on a fall position of recording information corresponding toeach recording mark length.

This reduces the amount of the heat accumulated at the rear edge of therecording mark, the heat increasing when an intermediate period betweenthe top pulse and the last pulse becomes longer as the recording marklength increases. That is, when the last section fall position of thepulse sequence for forming the recording mark whose length is not equalto but is longer than the predetermined recording mark length isrelatively shifted in an opposite direction to a time proceedingdirection (along a time axis), the intermediate period is shortened.This reduces the amount of the heat accumulated at the rear edge,thereby improving the jitter.

Also, in the recording parameter setting device of the presentinvention, it is preferable that the predetermined recording mark lengthis equal to or longer than 4T.

Thus, when the recording mark has a length equal to or longer than thepredetermined recording mark length at which the rear edge is supposednot to be affected by the heat accumulated at the front edge of therecording mark, that is, at which the recording parameter of the rearedge is supposed to be controlled separately from the recordingparameter of the front edge, the recording mark can be set so that theamount of the heat accumulated at the rear edge is reduced. This makesit possible to form a recording mark capable of surely providing a goodreproduced signal quality while the number of recording parameters to beused is reduced.

The foregoing means of the recording parameter setting device may beexecuted on a computer by using a program. Also, the program may beexecuted on a desired computer by storing the program in acomputer-readable recording medium.

The information recording medium of the present invention is configuredto contain, in a predetermined region, the recording parameter which isset by any one of the foregoing recording parameter setting devices.

This makes it possible to form a recording mark capable of surelyproviding a good reproduced signal quality while the number of recordingparameters to be used is reduced.

The recording/reproducing device of the present invention includes: anoptical pickup configured to carry out a recording process and areproducing process with respect to an information recording medium; andany one of the foregoing recording parameter setting devices.

This makes it possible to form a recording mark capable of surelyproviding a good reproduced signal quality while the number of recordingparameters to be used is reduced.

The invention being thus described, it will be obvious that the same waymay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

Industrial Applicability

A recording parameter setting device, a program thereof, acomputer-readable recording medium containing the program, aninformation recording medium, a recording/reproducing device, and arecording parameter setting method, each of which relates to the presentinvention, make it possible to form a recording mark capable of surelyproviding a good reproduced signal quality while the number of recordingparameters to be used is reduced. Therefore, the present invention ispreferably used in an industrial field where an information recordingmedium such as an optical disc and a magneto-optical disc is used,particularly in an industrial field where an information recordingmedium capable of recording at a high speed is used.

1. A recording parameter setting device configured to set recordingparameters for pulse sequences for forming recording marks on aninformation recording medium in accordance with recording information,comprising: a storage section or means for storing a first look-up tableand a second look-up table; and recording parameter setting means forsetting the recording parameters as the recording parameters of thesequences by obtaining, from the first look-up table and the secondlook-up table, recording parameters corresponding to the recordinginformation, the pulse sequences including: pulse sequences respectivelyforming recording marks of a first predetermined recording mark lengththrough a maximum recording mark length, the pulse sequences eachincluding: a top section including a top pulse; a last section includinga last pulse and a cooling period; and an intermediate section includingan intermediate period provided between the top section and the lastsection; and pulse sequences respectively forming recording marks of arecording mark length shorter than the first predetermined recordingmark length through a minimum recording mark length, the pulse sequenceseach including: a top section including a top pulse; and a last sectionincluding no last pulse and a cooling period, the first look-up tablestoring recording parameters for the top sections which recordingparameters control heat of front edges of the recording marks, whereinthe recording parameters for the top sections are classified inaccordance with at least recording mark lengths out of the recordinginformation, and, among the recording parameters for the top sections,recording parameters for the top sections of the first predeterminedrecording mark length through the maximum recording mark length areclassified into a same group, the second look-up table storing recordingparameters for the last sections which recording parameters control heatof rear edges of the recording marks, wherein the recording parametersfor the last sections are classified in accordance with at leastrecording mark lengths out of the recording information, and, among therecording parameters for the last sections, recording parameters forlast sections of a second predetermined recording mark length throughthe maximum recording mark length are classified into a same group, andthe second predetermined recording mark length is longer than the firstpredetermined recording mark length.
 2. The recording parameter settingdevice as set forth in claim 1, wherein: among the recording parametersfor the last sections, recording parameters for last sections forrecording mark lengths each of which is equal to or longer than thefirst predetermined recording mark length are classified into (a) agroup for a recording mark length which is equal to the firstpredetermined recording mark length and (b) another group for arecording mark length which is longer than the first predeterminedrecording mark length.
 3. The recording parameter setting device as setforth in claim 1, wherein: the recording parameters for the lastsections are respectively fall positions of the last sections; and amongthe fall positions of the last sections, fall positions of last sectionsfor recording mark lengths each of which is equal to or longer than thefirst predetermined recording mark length are classified into (a) agroup for a recording mark length which is equal to the firstpredetermined recording mark length and (b) another group for arecording mark length which is longer than the first predeterminedrecording mark length.
 4. The recording parameter setting device as setforth in claim 3, wherein: the fall positions of the last sections ofthe recording mark lengths each of which is equal to or longer than thefirst predetermined recording mark length are classified into (a) thegroup for the recording mark length which is equal to the firstpredetermined recording mark length and (b) said another group for therecording mark length which is longer than the first predeterminedrecording mark length; and a value set for a fall position of a lastsection for the recording mark length which is longer than the firstpredetermined recording mark length is different from a value set for afall position of a last section for the recording mark length which isequal to the first predetermined recording mark length.
 5. The recordingparameter setting device as set forth in claim 4, wherein: the fallposition of the last section for the recording mark length which islonger than the first predetermined recording mark length is set so asto be shifted, relative to the fall position of the last section for therecording mark length which is equal to the first predeterminedrecording mark length, in an opposite direction to a time proceedingdirection (along a time axis) based on a fall position of recordinginformation corresponding to each recording mark length.
 6. Therecording parameter setting device as set forth in claim 1, wherein: therecording parameters for the last sections are respectively coolingstart positions at which their corresponding cooling periods start. 7.The recording parameter setting device as set forth in claim 1, wherein:the recording parameters for the last sections are respectively coolingend positions at which the cooling periods end in their correspondingpulse sequences for forming the recording marks.
 8. The recordingparameter setting device as set forth in claim 1, wherein: the recordingparameters for the top sections are respectively rise positions of theircorresponding top pulses.
 9. The recording parameter setting device asset forth in claim 1, wherein: the recording parameters for the topsections are respectively widths of their corresponding top pulses. 10.The recording parameter setting device as set forth in claim 1, wherein:the first predetermined recording mark length is equal to or longer than4T.
 11. A recording parameter setting method for setting recordingparameters for pulse sequences forming recording marks on an informationrecording medium in accordance with recording information, said methodcomprising: (i) a first recording parameter classification step forclassifying, in accordance with at least recording mark lengths out ofthe recording information, recording parameters for top sections of thepulse sequences which recording parameters control heat of front edgesof the recording marks, while classifying, among the recordingparameters for the top sections, recording parameters for the topsections of a first predetermined recording mark length through amaximum recording mark length into a same group; and (ii) a secondrecording parameter classification step for classifying, in accordancewith at least recording mark lengths out of the recording information,recording parameters for last sections of the pulse sequences whichrecording parameters control heat of rear edges of the recording marks,while classifying, among the recording parameters for the last sections,recording parameters for last sections of a second predeterminedrecording mark length through the maximum recording mark length into asame group, the pulse sequences including: pulse sequences respectivelyforming recording marks of the first predetermined recording mark lengththrough the maximum recording mark length, the pulse sequences eachincluding: a top section including a top pulse; a last section includinga last pulse and a cooling period; and an intermediate section includingan intermediate period provided between the top section and the lastsection; and pulse sequences respectively forming recording marks of arecording mark length shorter than the first predetermined recordingmark length through a minimum recording mark length, the pulse sequenceseach including: a top section including a top pulse; and a last sectionincluding no last pulse and a cooling period, and the secondpredetermined recording mark length is longer than the firstpredetermined recording mark length.